The invention concerns a method of continuously producing hard-candy masses from an aqueous solution of starting ingredients by boiling and condensing the solution, subjecting it to a vacuum, condensing it further and cooling it, adding flavorings, dyes, etc., and finally cooling it again and shaping it into candy. The device for carrying out the method has a steam-heated coil-type boiler followed by a condenser, a vacuum chamber, and an extractor. The method is continuous and the device operates continuously.
A method and device of the aforesaid type are known from German Patent 3 336 187. The starting ingredients are sucrose and glucose syrup in an aqueous solution. This method and device accordingly concern the production of conventional hard sugar candy, candy made of or involving sugar. Once the starting ingredients have been mixed into and dissolved in the water, the solution is boiled in one or even in two stages in a coil-type boiler. The solution is pumped through the coil and heated with steam. The steam condenses on the tubing in the coil and heats the solution. The solution, which can be as hot as approximately 140.degree. C., travels from the boiler into an adjacent condenser, and the vapors are exhausted into the atmosphere. The resulting material can be approximately 97% dry. This solution, or mass, travels from the condenser into a chamber where it is subjected to a vacuum.
The reduction in pressure re-initiates boiling. The resulting vapors are exhausted with the same pump that establishes the vacuum. The mass accordingly cools down further and become even drier and more viscous. The residual water content may be as low as approximately 1.5%. Below the vacuum chamber is a screw that conveys the mass to a mixer, wherein flavorings, dyes, etc. and optionally air can be added to it. The mass must be viscous enough when it arrives in this extractor to ensure a seal that will permit maintenance of the vacuum. The mass is then conventionally cooled, shaped, and further processed. There are no problems in processing conventional sugar-based masses in these known systems.
In the continuous production of sugarless hard-candy masses, those that involve such sugar substitutes as xylitol, sorbitol, palatinitol, etc., the results of the known method are not satisfactory. The reason for this negative outcome is that the viscosity of a sugarless candy mass differs from that of a mass that contains sucrose and glucose syrup. At the same temperature and solids content, the viscosity of a sugarless mass will be substantially lower than that of a mass based on sucrose and glucose syrup. The sugarless mass will accordingly be much too fluid to ensure enough of a seal to maintain a vacuum in the extractor below the vacuum chamber. When starting ingredients in the form of sugar substitutes are handled in the production of hard-candy masses in the same way as the conventional sugar and glucose-syrup masses, the boiling stage cannot be followed by a vacuumizing stage because the continuously operating extractor can only apply enough pressure to maintain a constant vacuum when the mass being extracted has a system-dictated minimum viscosity.
One strategy that might suggest itself for combating the aforesaid problem in the production of hard-candy masses with starting ingredients in the form of sugar substitutes is to boil the solution at a high temperature, at up to approximately 165.degree. C., to reduce the content of residual water. Once a residual-water content of 1.5% has been attained at approximately 165.degree. C. for example, the vacuumization step will not, due to the small amount of residual water that can still evaporate, significantly alter the product (recooling by re-evaporation). Boiling the solution at as high as approximately 165.degree. C., however, also entails considerable drawbacks. First, the steam supply must be readjusted unless the device is to be operated at a lower output. Most flavorings are sensitive to heat, and only those that can resist relatively high temperatures can be employed. In spite of this, however, the resulting mass will still be too fluid, meaning that its viscosity will be too low to satisfy the special conditions involved in the further processing.